Biography

Sebs

Inter alia: academic, economist, bon vivant.
There will be more, meanwhile check my résumé.

Curriculum Vitae

Sebastian (I.S.) Buhai: Résumé with links (October 2014)
For a detailed Curriculum Vitae please download the
extended PDF version.


Contact Details

Visiting address:
Stockholm University
Department of Economics
Universitetsvägen 10 A
Frescati, Stockholm
House A, floor 7

Emails: sbuhai at gmail dot com

sebastian dot buhai at ne dot su dot se

Web: www.sebastianbuhai.com

Post address:
Stockholm University
Department of Economics
106 91 Stockholm
Sweden

Current/ Recent Academic Affiliations

Since 05/2013, I am Visiting Faculty at the Department of Economics, Stockholm University.
From the same date, I am also Associated Faculty at the Department of Economics and Business, Business and Social Sciences, Aarhus University.

Between 05/2010 – 05/2013 I was Marie Curie postdoctoral fellow, on a 3-year individual and independent International Outgoing Fellowship (IOF) awarded by the EU Commission under the FP7-People Marie Curie Actions Program, at the Department of Economics, Northwestern University (as “outgoing host”, first 2 of the 3 years), and the Department of Economics and Business, Business and Social Sciences, Aarhus University (as “EU host”, 3rd year). I was privileged and honored to have Dale Mortensen as scientific guide and mentor for this Marie Curie IOF, and beyond it.


Main Research Interests

Microeconometrics, Labor Economics, Real Options, Empirical Industrial Organization, Social Networks, Personnel Economics


Degree Education


Completed Research

* I maintain a more detailed page on my research in Economics, which also includes titles/ abstracts of other research in progress.

Peer-reviewed publications:

    Working papers:

    Published theses and scientific reports:

    Other disciplines than Economics:


    For more information and details please see my extended CV (PDF version).

    Research

    Sebastian Buhai’s Research in Economics

    Publications (peer-reviewed)

    Returns to Tenure or Seniority? (with Miguel Portela, Coen Teulings and Aico van Vuuren), March 2014, Econometrica, 82 (2), pages 705–730, DOI: 10.3982/ECTA8688 . See also the corresponding Web Appendix or the old July 2009 version (includes theory framework)

    This study documents two empirical facts using matched employer-employee data for Denmark and Portugal. First, workers who are hired last, are the first to leave the firm. Second, workers’ wages rise with seniority, where seniority is defined as a worker’s tenure relative to the tenure of his colleagues. Controlling for tenure, the probability of a worker leaving the firm decreases with seniority. The increase in expected seniority with tenure explains a large part of the negative duration dependence of the separation hazard. Conditional on ten years of tenure, the wage differential between the 10th and the 90th percentile of the seniority distribution raises is 1.1-1.4 percentage points in Denmark and 2.3-3.4 in Portugal.
    Keywords: wage dynamics, tenure, seniority, Last-In-First-Out
    JEL-codes:
    J31, J41, J63

    Tenure Profiles and Efficient Separation in a Stochastic Productivity Model (with Coen Teulings), May 2014, Journal of Business and Economic Statistics, 32:2, pages 245-258, DOI:10.1080/07350015.2013.866568 . See also the corresponding Web Appendix or the accepted, non-gated, November 2013 version. This paper had 2nd R&R at the Review of Economic Studies earlier.

    We develop a theoretical model based on efficient bargaining, where both log outside productivity and log productivity in the current job follow a random walk. This setting allows the application of real option theory. We derive the efficient worker-firm separation rule. We show that wage data from completed job spells are uninformative about the true tenure profile. The model is estimated on the PSID. It fits the observed distribution of job tenures well. Selection of favourable random walks can account for the concavity in tenure profiles. About 80% of the estimated wage returns to tenure is due to selectivity in the realized outside productivities.
    Keywords: random productivity growth, efficient bargaining, job tenure, inverse gaussian, wage-tenure profiles, option theory

    JEL-codes: C33, C41, J31, J63


    Working papers

    A Social Network Analysis of Occupational Segregation (with Marco van der Leij), latest version Nov 2013; current stage: updated version very soon

    We develop a social network model of occupational segregation between different social groups, generated by the existence of positive inbreeding bias among individuals from the same group. If network referrals are important for job search, then expected homophily in the contact network structure induces different career choices for individuals from different social groups. This further translates into stable occupational segregation equilibria in the labor market. We derive the conditions for wage and unemployment inequality in the segregation equilibria and characterize first and second best social welfare optima. Surprisingly, we find that utilitarian socially optimal policies involve segregation.
    Keywords: Social Networks, Homophily, Inbreeding Bias, Occupational Segregation, Labor Market Inequality, Social Welfare
    JEL codes: J24, J31, J70, Z13

    How Productive is Workplace Health and Safety? (with Elena Cottini and Niels Westergaard-Nielsen), latest version Sep 2014; current stage: submitted.

    This paper investigates the causal impact of workplace health and safety practices on firm performance, using Danish longitudinal matched employer-employee data merged with unique cross-sectional representative firm survey data on work environment conditions. We estimate standard production functions, augmented with workplace environment indicators, addressing both time-invariant and time-varying potentially relevant unobservables in the production process. We find positive and large productivity effects of improved physical dimensions of the health and safety environment (specifically, “internal climate” and “repetitive and strenuous work”).
    Keywords: occupational health and safety, work environment, firm performance, production function estimation
    JEL codes: C33, C36, D24, J28, L23

    Firm downsizing, public policy, and the age structure of employment adjustments (with Hans-Martin von Gaudecker), latest version Dec 2012; current stage: still preliminary, in revision.

    This paper studies the structure of workforce adjustments when firms facing adverse demand conditions are offered public financial incentives for downsizing. In particular, we are interested in how the age composition of employee outflows is shaped by corresponding age-dependent institutional arrangements. Our simple labour demand framework, with stochastic product demand and firing costs heterogenous in workers’ early retirement eligibility, has as core prediction that distressed firms will dismiss with predilection those employees eligible to retire early. We test the model’s implications on the entire set of mass layoff events in larger Danish private firms over 1980-2001, period covering several reforms to the early pension system. Our empirical conclusion is that that firms behave as predicted by our model with regards to their lower-educated workforce, but not towards their higher-educated employees. We suggest that an extension of our firm-level model to narrow within-firm employee categories with potentially asymmetric turnover responses to firm-level demand shocks can rationalize this finding.
    Keywords: early retirement, labour demand, employment adjustment, mass layoffs, LEED
    JEL-codes: H32, H55, J26, J65

    Work in Progress (and some temporarily abandoned projects)

    • Job Hazard Premia and Worker Risk Preferences (with Elena Cottini); draft available soon

    We provide a fresh analysis of the theory of compensating wage differentials (CWD) using unusually rich and detailed data on self-reported work environment conditions and worker risk attitudes, from a representative 4-wave (1990-2005, 5-year spaced) panel survey of workers, which we link to the Danish register, longitudinal, yearly, matched employer-employee data. Our study improves and extends previous CWD empirical analysis in several ways: a) in standard hedonic wage equations, we control for both individual and firm-specific time-invariant unobserved heterogeneity; we also report spell first-difference estimates where workers report changes in work conditions, within the same job spell; b) we account for worker heterogeneity in attitudes towards health and safety risks, from information on workers’ smoking habits, and on their being parents of young children; c) we compare the results in a) and b) above with alternative results obtained by estimating the workers marginal willingness to pay for job amenities from their job separation hazards. For a), we find that the only work environment conditions compensated for by hourly wage premia, in the order of 4-6%, are related to flexibility in the working time (“shift premia”), namely “working in irregular shifts”, “working in the evening” and “working at night”. If in addition we account for the selection of workers in hazardous jobs based on the observed worker risk proxies and time-invariant worker unobservables, cf. b), we find negative selection of risk-lovers into shift-jobs, with sizable hourly wage premia of 18-26%, while positive or no selection, and no compensation, in other types of hazard work. Finally, cf. c), shift-jobs CWD estimates based on the worker’s employment history have magnitudes in between those at a) and b). We rationalize our empirical results via a parsimonious model of job hazard premia and worker risk profiles.

    • Performance Pay, Wage Dispersion, and Job Separation (with Miguel Portela); draft available soon

    We investigate the effects of performance pay (PP) on individual wage growth, within and between-firm earnings inequality, and worker-firm separation, using exhaustive Portuguese linked employer-employee longitudinal data for 1986-2007. This is the first economy-wide study in the incentive compensation literature attempting to account for the endogenous compensation policy of firms and for endogenous selection of workers across PP and non-PP firms. In our empirical analysis we are able to control for both unobserved worker and unobserved firm specific heterogeneity, and to proxy for the firm’s costs of switching across PP and non-PP regimes. Inter alia, emphasis is placed on the determinants, effects, and dynamics of managerial incentive pay and turnover. We rationalize our findings by means of an extended Lemieux, MacLeod and Parent (2009, QJE) model.

    • Worker-Firm Dynamics with Seniority Bargaining: Theory and Empirics (with Coen Teulings and Miguel Portela)
    • A Real Options Theory of Labor Turnover
    • Business Cycles and the Age Structure of Labour Adjustments. Structural Framework and Empirical Assessment (with Hans-Martin von Gaudecker)
    • Employee Wage, Employer Size and Stochastic Labour Demand
    • Disentangling Labor Adjustment Costs (with Miguel Portela)
    • Recovering wage offer and employee productivity distributions in search models: an empirical investigation using Danish data (with Jesper Bagger)
    • Estimation of an Equilibrium Model of Firm Dynamics (with Julien Prat)
    • On Labour Market Transitions under Efficient Bargaining and Idiosyncratic Productivity Shocks (with Dimitris Pavlopoulos)
    • Structural Estimation of a Two-Sided Matching Employer-Employee Model (with Daniele Condorelli)
    • Peer Group Effects and College Choice (with Marisa Hidalgo Hidalgo)
    • Experimental Evidence on Fairness among Workers (with Jens Grosser)

    Published Dissertations & Reports

    Essays on Labour Markets: Worker-Firm Dynamics, Occupational Segregation and Workplace Conditions (Full Digital Version in the EUR Repository), PhD Thesis November 2008, Tinbergen Institute and Erasmus University Rotterdam, Thela Thesis -Academic Publishing Services, Amsterdam, The Netherlands, November 2008

    Wages, Seniority and Separation Rates in a Stochastic Productivity Model: A Comparative Perspective, MPhil Thesis in 2003, at the Tinbergen Institute, published as monograph at the Lumen Publishing House, Iasi, Romania, February 2006

    Quantile Regression: Overview and Selected Applications, Ad-Astra Journal (Young Romanian Scientists’ Journal), Vol. 4, 2005

    Note on Panel Data Econometrics, NAKE Nieuws 15 (2), December 2003

    Other unpublished work from my graduate student days (surveys, reports, course papers etc.)

    On Risk in Educational Choice: Brief Overview and Research Note, December 2003

    Investigating Reciprocal Motivation in Experimental Labor Markets, June 2003

    Incomplete Contracts and the Theory of the Firm, January 2003

    Job Search and Contact Networks, April 2002

    * See also a list of courses followed during my graduate programs, with links to the instructors’ webpages (for external summer schools and workshops see my extended CV).

    Essays

    Sebastian Buhai’s Miscellaneous Essays

    You can read a selection of my undergrad student essays at University College Utrecht/ Utrecht University on this page. The rest of the documents linked to below are mostly in Romanian, although the explanations around them are still in English. You can also find some of my public opinions in press interviews accessible via my media-coverage page.

    NB. Click on the pdfs.gif<br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br />             (158 bytes) images to download copies of these articles (or follow the direct links if they were published somewhere online; however, some of those links do not work any longer).

    Selection of some more recent (from 2007 onward) essays/ presentations:

    • pdfs.gif<br /><br /><br />             (158 bytes) Detailed answers to what finally became an unpublished 10-questions “interview” requested by Romanian national newspaper “Romania Libera”, 10 February 2012 (in Romanian)
    • pdfs.gif (158 bytes) An article entitled “Unii dintre noi vom avea atâta timp liber încât ne vom plictisi. Altii deloc…” I wrote for the Romanian newspaper Cotidianul in their series “5000 semne ale viitorului”, published on the 20th of April 2008 (some info about the series in this article by Alexandra Badicioiu). The article linked above also contains some biographical information (both the article and the information have been edited by the journalists from Cotidianul to fit the required space and the format). If the direct link above stops functioning properly, you have above a link to the version saved on my site. There are also some more details and further references to the article linked here in the comments section of this post on my blog.
    • pdfs.gif (158<br /><br /><br />               bytes) Scientific Colloquium of Romanian researchers in Denmark, at the residence of the Romanian Ambassador in Denmark, Theodor Paleologu, on the 10th of March 2007. I presented “Economia ca stiinta sau despre imperialismul economic intre stiintele sociale”; you can dowload the PDF presentation linked at the start of this paragraph (in Romanian). I talked a bit more about this colloquium on my blog (also in Romanian). And you can also find something about this event on the site of the Romanian Embassy in DK.

    Below you can read a few older (before 2007) articles and presentations, on various topics, published in various Romanian mass-media (online and/or in print format), aimed for the large public. In general I tried to keep the order chronological, as from most recent to oldest, but that is not always guaranteed…

    First some short articles (in the un-edited version) published within the Educational Supplement of the newspaper Gandul, on the lives of several Nobel Laureates (that section is actually called, in direct translation from Romanian, “the Nobel Laureates are also humans…”). I don’t know yet if I will continue with this series.

    • John Harsanyi: O Calatorie Incredibila sau “Daca Vrei cu Adevarat, Poti!” (You can also read this from my blog)- this has not been published in Gandul yet (or this is what I know, it sounds incredible but I am actually never informed whether something was published, will be published and so on- another reason why I am not sure whether it is worth continuing- my 100% voluntary- collaboration there).
    • Jan Tinbergen: Un Om de Stiinta Coborat din Turnul de Fildes (I posted this also on my weblog, here).
    • Jim Heckman: Independenta, Perseverenta, Excelenta. Punct si de la Capat… (You can also access it via my weblog)

    I also published a very short economic article (the most difficult part was to keep it that short) in the newspaper Cotidianul.

    • Snapshot Economic al Europei in Tranzitie: Noiembrie 2005 .You can also read it directly on their site (I also posted it on my weblog).

    I wrote another article

    • Liber-Schimbismul,. Protectionismul si…Amatorismul

    initially for the same newspaper Cotidianul but apparently they did not like it (I say “apparently”, since in fact I was never given a reason for “why not”, which is what I would have expected from rational people) so at the very end of the day I ended up just posting it on my blog. Well, who’s interested will find it, read it and- you’re welcome to, by the way- comment on it and on anything else that you find on this page.

    I continue with some articles that were initially published on the Romanian online independent portal “Romania, Libera in Viitor” (RLIV), within its weekly electronic publication called “ACUM” (you can find all other articles I wrote for RLIV-ACUM here) and sometimes also in other places.

    Highlights (especially articles concerned with science and research policy in Romania):

    • Perspectiva Candidatilor la Presedintie asupra Cercetarii, Stiintei si Tehnologiei. Exemplul SUA, Deziderat in Romania

    My questions concerning the status of scientific research in Romania from the second part of this article (the essay was published here, in the RLIV-ACUM’s “Research, Science, Technology” (in Romanian: “Cercetare, Stiinta, Tehnologie”) section that I founded and maintained as editor until June 2005), inspired from the questions addressed by the prestigious journal Science to the USA presidential candidates and addressed to the Romanian presidential candidates in 2004, were publicly sustained by means of open letters, by the Ad-Astra Association of Romanian Researchers (in Romanian: Asociatia “Ad-Astra” a Cercetatorilor Romani), the Romanian Academic Forum (in Romanian: Forumul Academic Roman=FAR) and by several scientists of Romanian origin, including the Nobel Prize Laureate, Professor George Emil Palade. Some accounts in the mass-media and on the web sites of the organizations involved can be read in what follows: press communicate FAR, press communicates Ad-Astra, open letter signed also by Prof. Palade, other echoes in the Romanian mass-media: Evenimentul Zilei (also here and here), Ziua (also here), Romanian Global News (also here). Two of the Romanian presidential candidates answered the questions, Mr. Marko Bela and Mr. Adrian Nastase. A reaction of FAR to these two answers can be read here.

    • Renasterea Prestigiului Doctoral in Romania

    This short essay is the result of a joint brainstorming of several Romanian scientists working in research outside Romania, voluntarily organized in a taskforce to help the Romanian Ministry of Education in its planned reform of the Romanian High Education and Research sectors- it summarizes imperative measures needed to reform the doctoral programs in Romania and to consequently contribute to the rebirth of the Romanian doctoral prestige. It was published here, in the section “Cercetare, Stiinta, Tehnologie” of RLIV-ACUM. Miruna Munteanu wrote an excellent article related to this document in Ziua.

    • Conditia Cercetatorului Stiintific: Intre Realitatea de Acasa si Idealul din Afara

    I wrote this essay linked above for the conference “Migration of Young Romanian Researchers: Performances and Possibilities of Return”, organized by the Romanian Cultural Institute (Institutul Cultural Roman=ICR) in Sinaia,October 2004. The essay can be found on the site of the ICR, it was published also on RLIV-ACUM (here with the abstract in the beginning as well), and in the Ad-Astra Journal.

    • PDF Presentation of the paper “Conditia Cercetatorului…” (plus some other thoughts), at the Sinaia conference mentioned above

    Some people in the audience totally disagreed with me :-), but that presentation got me something like 11 subsequent interviews with Romanian TV channels and press…

    Other- random- articles published an era ago, in RLIV-ACUM (selection):

    • Scurt despre Zei si Pamanteni in Context Autohton
    • Cum Clavis: Modul de Alegere a Viitorului Papa
    • Opinia Cititorului: Cu Trenul prin Romania. Partea a II-a
    • A Face o Diferenta
    • Noteaza-ti profesorii: www.calificativ.ro
    • Reflectii (Utopice) de Duminica Seara pe Tema Societatii Civile Active
    • Opinia Cititorului: Cu Trenul prin Romania
    • Cat de Fioros Este Leul Greu? Despre Implicatiile Denominarii Monedei Nationale din Iulie 2005
    • Consideratii Subiective asupra Retoricii Publice: Logos, Pathos, Ethos in Versiune Mioritica
    • Note de Trecere, Mizerii si Dogme
    • Elitele Autohtone: Conflict si Mediocritate (Pledoarie pentru Cooperare)
    • Plesu si Mancatorii de Sarmale
    • Un ecou la “Elementele Nonverbale…”
    • Ma-Ia-Hii, Ma-Ia-Huu, Ma-Ia-Hoo, Ma-Ia-Haa si Adevarata Muzica Romaneasca
    • Germania de Est: Popularitate Ingrijoratoare a Extremismului Politic
    • Performanta Economica a Presedintilor Americani in Perioada Postbelica
    • Talmaciri din Harry Mulisch: “Descoperirea Paradisului”
    • “Cercetare, Stiinta, Tehnologie”: O Rubrica la Inceput de Drum
    • 15 milioane de Oameni
    • Fahrenheit 9/11- FILMUL


    Media Coverage

    Mass-media coverage of Sebastian Buhai

    A selection of press/ magazine articles & other media, including, e.g., television interviews/talk-shows (in various languages, see in the brackets next to the links) where I have been interviewed/ invited/ mentioned (and saved PDF versions – by clicking on pdfs.gif (158 bytes) below – where possible, should the direct links not work any longer, which is unfortunately the case for many…). The starred ones Starredare larger contributions (such as, for instance, longer interviews). In reverse chronological order:

    Projects & Links

    Sebastian Buhai’s Projects and Links

    [Sebi's photo gallery online]
    Browse Sebi’s Flikr Sets

    [blog.sebastianbuhai.com]
    Read my favourite blog.

    [twitter.com/sbuhai]
    Check out my favourite twitter feed.

    [econacademia.net]
    I am initiator & co-founder of this portal for Romanian Academic Economists.

    [blog.econacademia.net: in preparation]
    I am initiator & co-founder of this blog for Romanian Academic Economists.

    See also a bunch of random links from my older web site, which I will organize as soon as possible…